Who discovered the neutron? a) J.J. Thomson b) Chadwick c) Rutherford d) Priestley Answer: b
Which of the following elements has a higher atomic number than copper? a) Iron b) Chromium c) Zinc d) Manganese Answer: c
The photoelectric effect involves the emission of electrons when: a) The metal is heated b) The metal is placed in an electric field c) High-speed electrons strike the surface d) Light of suitable frequency falls on the metal surface Answer: d
An atomic orbital is defined as: a) A circular path of the electron b) An elliptical orbit c) A three-dimensional region around the nucleus d) A region where the probability of finding an electron is maximum Answer: d
Bohr’s model successfully explains: a) The spectrum of hydrogen atoms b) The spectrum of any atom with two electrons c) The spectrum of hydrogen molecules d) The solar spectrum Answer: a
When an electron falls from a higher to a lower energy level: a) Energy is absorbed b) Energy is emitted c) Atomic number increases d) Atomic number decreases Answer: b
Atoms of different elements have: a) Same atomic number and configuration b) Different atomic number but same configuration c) Different atomic number and different valence electrons d) Same number of electrons and neutrons Answer: c
The concept of dual nature of radiation was proposed by: a) Max Planck b) De Broglie c) Heisenberg d) Pauling Answer: b
An element has atomic number 17 and mass number 36. How many neutrons are present? a) 17 b) 19 c) 36 d) 53 Answer: b
The element with atomic number 29 belongs to: a) s-block b) d-block c) p-block d) f-block Answer: b
The antiparticle of an electron is: a) Positron b) Proton c) Alpha particle d) Beta particle Answer: a
Fundamental particles of an atom include: a) Proton, electron, meson b) Proton, electron, photon c) Proton, electron, neutron d) Proton, electron, deuteron Answer: c
The species ⁴⁰Ar₁₈, ⁴⁰K₁₉, ⁴⁰Ca₂₀ are called: a) Isotones b) Isotopes c) Isobars d) None of these Answer: c
The order of orbital filling in atoms is governed by: a) Aufbau principle b) Heisenberg uncertainty principle c) Hund’s rule d) Pauli’s exclusion principle Answer: a
When metals are heated in flame, electrons jump to higher energy levels. On returning to lower levels, they emit: a) Raman spectrum b) Absorption spectrum c) Emission spectrum d) Fluorescence Answer: c
Regarding Bohr’s atomic model, which are correct?
It introduces stationary orbits
It assumes quantized angular momentum
It uses a planetary model with circular orbits a) 1 and 2 b) 2 and 3 c) 1 and 3 d) 1, 2 and 3 Answer: d
Atomic size is approximately: a) 10⁻⁸ cm b) 10⁻¹⁰ cm c) 10⁻¹³ cm d) 10⁻⁶ cm Answer: b
Which of the following is NOT true about X-rays? a) They have low energy b) They travel at the speed of light c) They can be refracted d) They affect photographic plates Answer: a
The size of the atomic nucleus is measured in: a) amu b) Angstrom c) cm d) Fermi Answer: d
Which element has only two electrons in the K-shell? a) Hydrogen b) Helium c) Neon d) Sulphur Answer: b
The nucleus of an atom contains: a) Protons b) Neutrons c) Protons and neutrons d) Electrons, protons, and neutrons Answer: c
Which of the following is NOT a nucleon? a) Proton b) Electron c) Neutron d) Positron Answer: b
Number of p-electrons in a bromine atom: a) 12 b) 15 c) 7 d) 17 Answer: d
Which particle has the greatest mass? a) Electron b) Proton c) Neutron d) Hydrogen nucleus Answer: c
The mass of a proton is approximately equal to the mass of a: a) Neutron b) Electron c) Isoprone d) Alpha particle Answer: a
